PITTSBURGH (Reuters) - Protesters demonstrating against capitalism at the Group of 20 summit ran through central Pittsburgh on Thursday, smashing shop windows as police in riot gear used pepper gas and batons to disperse them.
During the evening rush hour in Bloomfield, Pittsburgh's Little Italy, about 300 rowdy protesters remained from a crowd that originally numbered 2,000. Some threw rocks at police.
The crowd broke windows at Boston Market and KFC fast-food restaurants, a BMW dealership and a Fidelity bank in the area, about a mile from the fenced-off convention center where the G20 talks were taking place.
Police in body armor with plastic shields threw pepper gas canisters and fired pellet-filled "beanbags" to disperse the protesters, charging in to make some arrests.
Protests -- usually against some aspect of capitalism -- have marked major gatherings of world leaders on the economy for years, sometimes turning violent and forcing summit organizers to use fortress-like security.
Earlier, police dispersed the 2,000 people who had gathered during lunchtime for a march.
"You must leave the immediate vicinity regardless of your purpose," police said over bullhorns throughout the march and warned that gas and other "non-lethal force" would be used.
With protesters sent down various streets by police, the two sides clashed in the Lawrenceville neighborhood.
Protesters threw bottles and police responded by sending five to 10 canisters into the crowd. The sharp smell of the gas irritated the eyes and throats of protesters, some of them vomiting as they ran.
"We have seen police use rubber bullets, batons and gas," said Noah Williams, a spokesman for the anti-capitalist Pittsburgh G20 Resistance Project.
Leaders of 19 leading developed and developing economies and the European Union are meeting on Thursday and Friday in Pittsburgh for a gathering to discuss how to improve financial reforms to avoid another global economic crisis.
A G20 meeting in London in April drew several thousand people to protests that began peacefully before turning violent, with one person collapsing and dying.
U.S. Secret Service spokesman Darrin Blackford said the gas used on Thursday was OC Vapor, which contains the active ingredient in pepper spray and causes the eyes to tear.
He confirmed three people were arrested and said he had unconfirmed reports of another four. He denied local media reports that police used rubber bullets on the crowd.
The marchers overturned dumpsters and hurled anything they could find at police, who gave chase and broke them into ever smaller groups.
Ear splittingly loud sirens sent protesters fleeing.
Protesters wore bandannas and goggles and held aloft a large black sign declaring "No hope in capitalism" and another saying "Kick Capitalism While It Is Down."
Another sign simply said "I'm mad as hell."
"We're here to put pressure on the G20 to ultimately abolish global capitalism," said a 24-year-old man from Delaware, who declined to give his name.
Justin Hershkovitz, 26, a student from Michigan, complained about the police tactics as he ran from the officers.
"This kind of force has been used as an option of first resort by cops (at summits) in Italy, London and now Pittsburgh," he said.
As protesters ran through Pittsburgh's Strip District, some residents stood in their doorways cheering them on.
"Get a job," one man shouted at a running demonstrator.
Protesters plan a series of actions on Friday outside "institutions that the G20 protects and defends," including Starbucks, Gap, McDonald's and banks.